Where do the pectoralis muscles attach?

From the Guidelines

The pectoralis muscles attach to specific locations on the chest and upper arm, with the pectoralis major originating from the clavicle, sternum, and cartilages of ribs 1-6, and inserting onto the lateral lip of the bicipital groove of the humerus, while the pectoralis minor originates from ribs 3-5 and inserts onto the coracoid process of the scapula. The attachment points of the pectoralis muscles are crucial for their functions, including adduction, flexion, and internal rotation of the arm by the pectoralis major, and stabilization of the scapula and assistance with breathing by the pectoralis minor. Understanding these attachment points is essential for proper exercise technique and clinical assessment of chest and shoulder injuries, as noted in studies discussing thoracic outlet syndrome and the anatomy of the thoracic outlet 1. Key points about the attachment of the pectoralis muscles include:

• The pectoralis major muscle attaches to the clavicle, sternum, and cartilages of ribs 1-6, and inserts onto the lateral lip of the bicipital groove of the humerus.
• The pectoralis minor muscle attaches to ribs 3-5 and inserts onto the coracoid process of the scapula. These attachment points allow the pectoralis muscles to perform their functions, including movement of the arm and stabilization of the scapula. In the context of thoracic outlet syndrome, understanding the anatomy of the thoracic outlet, including the attachment points of the pectoralis muscles, is important for diagnosis and treatment, as noted in studies discussing the use of imaging modalities such as CT and MRI to evaluate the thoracic outlet 1.

From the Research

Pectoralis Muscle Attachment

The pectoralis muscles attach to the following locations:

• The clavicular head of the pectoralis major muscle originates from the anterior surface of the medial half of the clavicle 2
• The sternocostal head of the pectoralis major muscle originates from the anterior surface of the sternum, superior six costal cartilages, and aponeurosis of the external oblique muscle 2
• The pectoralis minor muscle lies deep to the pectoralis major muscle, positioned on top of the rib cage 2
• The pectoralis major muscle inserts on the humerus, with the exact point of insertion being relevant to the mechanism of injury in cases of rupture 3, 4, 5

Muscle Function and Injury

The pectoralis muscles play a crucial role in the function of the upper extremity, and injuries to these muscles can significantly impact an individual's quality of life 6

• The pectoralis major muscle is involved in flexion, adduction, and internal rotation of the arm 6
• Ruptures of the pectoralis major muscle can occur due to violent, eccentric contraction of the muscle, often resulting from activities such as weight-lifting 3, 4, 5